This relates in general to light transmission and distribution systems comprising light guides and more particularly, to such a system in which the transmitting light guide serves as a primary light source.
For some years, optical fibers have been utilized in the prior art for transmitting optical energy from a source to a preselected destination with minimal energy loss along the transmission path. Accordingly, as described in detail in an article entitled The Fiber Light Guide by Alan G. Chenoweth, Vol. 29, No. 5, May 1976 of Physics Today, page 28 et seq., and in U.S. Pat. No. 3,641,332, issued to Franklin G. Reick and Michael Ebert, Feb. 8, 1972, for Fiber Optics Illumination System, the principal object of such systems is to practically eliminate the lateral diffusion of the optical rays from the core during course of light transmission. This is accomplished by forming the optical transmission core of a material which has a substantially higher index of refraction than the surrounding sleeve. This is enhanced, as disclosed in U.S. Pat. No. 3,641,332, supra, by interposing an annular layer of air between the core and the surrounding sleeve. The light from a source at one end of the optical fiber, or bundle of fibers, is totally reflected from the periphery back toward the center of the core, so that almost no energy is lost through the sidewalls of the transmitting fiber, and almost the entire light energy from the source is delivered to the selected destination at the other end. Thus, the sidewalls of the transmitting fiber or bundle of fibers, appear dark, and unable to function as a primary light source.
Line or strip sources of light are provided in the prior art by elongated tubes filled with rare gases, such as neon or argon. These are inexpensive to fabricate and install and require high voltages to operate.
Further, prior art safety signs and the like are fabricated using reflecting strips, which act as secondary sources of light. But none of the foregoing is fully satisfactory for safety or other utilitarian purposes, or for decorative purposes.